Composite Solid Polymer Electrolyte Research Articles

Self‐Supporting Solid Electrolyte Based on Supramolecular Interaction for Stable Li Metal Batteries

Li metal batteries based on solid polymer electrolytes offer the benefits of high energy density and safety, as well as extended cycling life, making them an excellent candidate for the next‐generation battery system. However, current solid polymer electrolytes still suffer from low ion conductivity and Li+ transfer number, which seriously restricts its practical application. Herein, a self‐supporting composite solid polymer electrolyte was prepared, where phenolic resin rich in hydroxyl groups (BR) and polyethylene oxide (PEO) are mixed evenly and poured onto a cellulose membrane in one step. In such an electrolyte, PEO and BR combine to form intermolecular hydrogen bonds, lowering the crystallinity of PEO and increasing the Li+ transfer number. Lastly, the obtained solid electrolytes exhibited a high ion conductivity (1.1×10‐4 S cm‐1) and Li+ transfer number (0.53), as well as improved electrochemical window. Consequently, Li || Li symmetrical cells can run stably for more than 700 h at 0.1 mA cm‐2/0.25 mAh cm‐2. And full cells with LiFePO4 cathode can also demonstrate high discharge capacity of 152.12 mAh g‐1 and rate performance. We believe that such a design based on supramolecular interaction offer a new avenue to advanced solid polymer electrolytes.

A-LLTO Nanoparticles Embedded Composite Solid Polymer Electrolyte for Room Temperature Operational Li-metal Batteries.

Solid-state batteries (SSBs) have the potential to revolutionize the current energy storage sector. A significant portion of the current development of electric vehicles and the electrification of various appliances relies on Lithium (Li)-ion batteries. However, future energy demands will require the development of stronger and more reliable batteries. This report presents a novel solid state electrolyte (SSE) composed of a self-healing composite solid polymer electrolyte (CSPE) matrix and aluminum-doped (Li0.33La0.56)1.005Ti0.99Al0.01O3 (A-LLTO) nanofillers. The CSPE contains Jeffamine ED-2003 monomer, Benzene-1,3,5-tricarbaldehyde (BTC)crosslinker dissolved in a 1:1 ratio of Dimethylformamide (DMF) to LiPF6, and a certain amount (x) of A-LLTO nanofillers (x=5, 7.5, 10, 12.5%). A CSPE containing x-amount of A-LLTO fillers (referred to as CAL-x%) demonstrates excellent ion-conducting properties and stable battery performance. The CAL-10% demonstrates 1.1×10-3Scm-1 of ionic conductivity at room temperature (RT). A-LLTO nanofillers dispersed uniformly within the polymer matrix form a percolation network, which is believed to improve ionic conductivity and the diffusion of Li+ ions. The CR-2032 cell, consisting of LiFePO4 (LFP)║CAL-10%║Li, at RT offers an initial discharge capacity of ≈165mAhg-1 at 0.1C rate for 120 cycles with 98.85% coulombic efficiency (C.E.).

Composite polymer electrolyte facilitated by enhanced amorphousity and Li+ conduction using LaFeO3-embedded PVDF-HFP for Solid-State lithium metal battery

Composite polymer electrolytes (CPEs) are a promising alternative to flammable conventional liquid electrolytes for high-safety lithium-ion batteries. Establishing low-cost filler that enhances the amorphous nature of polymer in the CPEs and exhibits efficient Lewis acid-base interaction between fillers and anions of lithium salt, leading to improved dissociation of salts for enhanced conduction, is indispensable. In this work, for the first time, we construct a solid composite polymer electrolyte of poly(vinylidene fluoride hexafluoropropylene) embedded LaFeO3 (LFO) particles prepared by solution casting and electrospinning methods and study their performances. The 5 wt% LFO filler embedded CPE made by means of solution casting and electrospinning methods exhibited the highest ionic conductivity of 5.9 × 10-4 and 1.49 × 10-3 S cm−1 at room temperature and electrochemical stability window up to 4.6 and 4.45 V, respectively. Further, as-assembled solid-state lithium-ion batteries using electrospun CPE showed an initial discharge capacity of 166 mAh/g at 0.1C-rate and solution-casted CPE showed excellent cycling stability with 98.6 % capacity retention at 0.3C-rate even at 50th cycle. Such excellent performance originated from the introduction of the LFO particles as filler into the polymer matrix to enhance the ionic conductivity, mechanical strength and lithium metal compatibility of the resulting CPEs.

Building Bulk and Interface Dual Fast Li+ Conducting Pathway in Composite Solid Polymer Electrolyte Membrane for All–Solid–State Lithium–Metal Batteries

AbstractSolid polymer electrolytes (SPEs) are considered a promising solution to the safety problems of lithium‐ion batteries (LIBs) using liquid electrolytes. However, the high crystallinity and low ionic conductivity hinder the practical application of SPEs. Herein, we design a composite solid polymer electrolyte with a dual fast Li+ conducting pathway in bulk and interface by incorporating highly Li+ conductive ceramic Li6.4Ga0.2La3Zr2O12 (LGLZO) in polyethylene oxide (PEO)/Li–bis (trifluoromethanesulfonyl) imide (LiTFSI) system. Compared to Li6.5La3Zr1.5Ta0.5O12 (LLZTO), LGLZO provides better Li+ conductivity; therefore, a fast Li+ conducting pathway will form in the bulk of LGLZO nanofillers. Besides, LGLZO nanofiller accelerates the dissociation of LiTFSI and benefits the transfer of free Li+ through the SPEs near the LGLZO surface, forming another interface fast Li+ conducting pathway in the SPEs. Benefits from the dual fast Li+ pathway design, the composite electrolyte membrane with 15 wt % LGLZO nanoparticles presents a high ionic conductivity of 8.0×10−4 S cm−1 at 60 °C. The Li−Li symmetric cells with optimized content LGLZO show good cycling stability (no short circuit even after 1000 h), and the all–solid Li/LiFePO4 batteries exhibit excellent cycling performance (remained 154 mAh g−1 after 500 cycles at 0.2 C under 60 °C).

Sandwich-type composited solid polymer electrolytes to strengthen the interfacial ionic transportation and bulk conductivity for all-solid-state lithium batteries from room temperature to 120 °C

The insurmountable charge transfer impedance at the Li metal/ solid polymer electrolytes (SPEs) interface at room temperature as well as the ascending risk of short circuits at the operating temperature higher than the melting point, dominantly limits their applications in solid-state batteries (SSBs). Although the inorganic filler such as CeO2 nanoparticle content of composite solid polymer electrolytes (CSPEs) can significantly reduce the enormous charge transfer impedance at the Li metal/SPEs interface, we found that the required content of CeO2 nanoparticles in SPEs varies for achieving a decent interfacial charge transfer impedance and the bulk ionic conductivity in CSPEs. In this regard, a sandwich-type composited solid polymer electrolyte with a 10% CeO2 CSPEs interlayer sandwiched between two 50% CeO2 CSPEs thin layers (sandwiched CSPEs) is constructed to simultaneously achieve low charge transfer impedance and superior ionic conductivity at 30 °C. The sandwiched CSPEs allow for stable cycling of Li plating and stripping for 1000 h with 129 mV polarized voltage at 0.1 mA cm−2 and 30 °C. In addition, the LiFePO4/Sandwiched CSPEs /Li cell also exhibits exceptional cycle performance at 30 °C and even elevated 120 °C without short circuits. Constructing multi-layered CSPEs with optimized contents of the inorganic fillers can be an efficient method for developing all solid-state PEO-based batteries with high performance at a wide range of temperatures.

Configuration design toward sustainably-released polymer electrolytes for enhancing ionic transport and cycle stability of solid lithium batteries

Poly(vinylidene difluoride) (PVDF)-based solid polymer electrolytes (SPEs) hold great promise in the practical deployment of solid lithium batteries (SLBs), but suffer from low ionic conductivity, poor interfacial compatibility, and unstable anode interface, especially without liquid wetting. Herein, we utilize poly (propylene carbonate) (PPC), which degrades into propylene carbonate (PC) when being contacted with alkaline Li-metal to construct the PVDF-based composite SPEs. Blended and bi-layered PVDF/PPC configurations are designed, of which the sustain-release effect of PPC, the ionic transport, and the cycle stability are compared. The evenly swelling of PC on PVDF enables a high ionic conductivity (1.2 × 10−4 S cm−1) and a low interfacial resistance (42 Ω cm−2) of bi-layered SPEs at 30 °°C and contributes to the homogeneous distribution of high current density inside electrolytes. Besides, the produced PC can accelerate the dissociation and decomposition of Li-salts, leading to the generation of a stable and uniform solid electrolyte interface. Consequently, the Li/LiFePO4 and Li/LiNi0.6Co0.2Mn0.2O2 cells with bi-layered SPEs deliver a capacity of 163.1 and 151.4 mAh g−1 for 100 cycles at 0.2 C and 30 °C. This study provides a rational protocol for the design of PVDF SPEs and promotes the practical application of PVDF-based SLBs with desirable performances.

Vertically-Aligned Card-House Structure for Composite Solid Polymer Electrolyte with Fast and Stable Ion Transport Channels.

All-solid-state lithium batteries (ASSLBs) are highly promising as next-generation energy storage devices owing to their potential for great safety and high energy density. This work demonstrates that composite solid polymer electrolyte with vertically-aligned card-house structure can simultaneously improve the high rate and long-term cycling performance of ASSLBs. The vertical alignment of laponite nanosheets creates fast and uniform Li+ ion transport channels at the nanosheets/polymer interphase, resulting in high ionic conductivity of 8.9 × 10-4 S cm-1 and Li+ transference number of 0.32 at 60°C, as well as uniformly distributed solid electrolyte interphase. Such electrolyte is characterized by high mechanical strength, low flammability, excellent structural stability and stable ion transport channels. In addition, the ASSLB cell with the electrolyte and LiFePO4 cathode delivers a high discharge specific capacity of 124.8 mAh g-1 , which accounts for 85.6% of its initial capacity after 500 cycles at 1C. The reasonable design through structural control strategy by interconnecting the vertically-aligned nanosheets open a way to fabricate high performance composite solid polymer electrolytes.

Solvent free PEO-NaClO4:Na3Zr2Si2PO12 composite solid polymer electrolytes: Comparison of conductive properties of “ceramics-in-polymer” and “polymer-in-ceramics”

In this work, a comparative study of the conductive properties of the PEO-NaClO4:NZSP composite solid polymer electrolyte (SPE) films was carried out in a wide range of the NZSP filler content (5–250 wt%), and the “ceramics-in-polymer” and “polymer-in-ceramics” fields were studied. The optimal composition of EO:NaClO4 with molar ratio is 10:1 to obtain SPE films with low crystallinity (12.2%) and high ionic conductivity (1.7·10−5 S·cm−1 at 30 °C) was determined. An additional reduction in crystallinity to 4.5% was achieved due to the introduction of NZSP filler. High ionic conductivity and low apparent activation energy were obtained with a content of NZSP filler of 25 wt% (σ = 3.56·10−5 S·cm−1 (30 °C) and Ea = 0.118 eV) for “ceramics-in-polymer” and 150 wt% (σ = 2.74·10−5 S·cm−1 (30 °C) and Ea = 0.116 eV) for “polymer-in-ceramics” fields. The Na+ ion transference number tNa+ was determined for PEO-NaClO4 and PEO-NaClO4:NZSP composites. The introduction of NZSP filler increases tNa+ from 0.45 (EO:NaClO4 = 10:1) to 0.55 (25 wt% of NZSP filler) and 0.77 (150 wt% of NZSP filler). The NVP||PEO-NaClO4:NZSP-150 wt%||Na half-cell was tested at 60 °C and the average charge-discharge capacity of ∼60 mAh·g−1 was achieved.

Solid-State Lithium Batteries with Ultrastable Cyclability: An Internal-External Modification Strategy.

A commonly used strategy to tackle the unstable interfacial problem between Li1.3Al0.3Ti1.7(PO4)3 (LATP) and lithium (Li) is to introduce an interlayer. However, this strategy has a limited effect on stabilizing LATP during long-term cycling or under high current density, which is due in part to the negative impact of its internal defects (e.g., gaps between grains (GBs)) that are usually neglected. Here, control experiments and theoretical calculations show clearly that the GBs of LATP have higher electronic conductivity, which significantly accelerates its side reactions with Li. Thus, a simple LiCl solution immersion method is demonstrated to modify the GBs and their electronic states, thereby stabilizing LATP. In addition to LiCl filling, composite solid polymer electrolyte (CSPE) interlayering is concurrently introduced at the Li/LATP interface to realize the internal-external dual modifications for LATP. As a result, electron leakage in LATP can be strictly inhibited from its interior (by LiCl) and exterior (by CSPE), and such dual modifications can well protect the Li/LATP interface from side reactions and Li dendrite penetration. Notably, thus-modified Li symmetrical cells can achieve ultrastable cycling for more than 3500 h at 0.4 mA cm-2 and 1500 h at 0.6 mA cm-2, among the best cycling performance to date.

CO2‐Assisted Induced Self‐Assembled Aramid Nanofiber Aerogel Composite Solid Polymer Electrolyte for All‐Solid‐State Lithium‐Metal Batteries

AbstractAll‐solid‐state lithium metal batteries (ASSLMBs) hold great promise for the development of next‐generation high‐safety, high‐energy‐density lithium batteries, but still face the challenges of lithium dendrite growth and thickness. Herein, the ultrathin PEO‐based composite solid polymer electrolyte (denoted as PAL) supported by a low‐density self‐supporting aramid nanofiber (ANF) aerogel framework is developed. The ANF aerogel obtained by a novel CO2‐assisted induced self‐assembly method has a well‐designed bilayer structure with double cross‐linking degree. Benefiting from the intermolecular interaction between ANFs and PEO, the PAL achieves an ultrathin thickness (20 µm) with excellent thermal stability and mechanical strength. Meanwhile, due to the modulation of ionic pathways by the functionalized ANF, the PAL achieves uniform lithium deposition without dendrites, resulting in stable long cycling (1400 h) for symmetric cells. Consequently, the Li|PAL|LiFePO4 (LFP) cell has excellent long‐term cycling stability (1 C, >700 cycles, Coulombic efficiency > 99.8%) and fast charge/discharge performance (rate, 10 C). More practically, the Li|PAL|LFP cell achieves an energy density of 180 Wh kg−1 due to the ability to match a high‐loading (8 mg cm−2) cathode. Furthermore, the double‐layer Li|PAL|LFP pouch cell demonstrates excellent flexibility and safety in cycling and abuse tests.

Interface Modification of LATP-Based Solid-State Li Metal Batteries Using Composite Polymer Electrolyte and Li-in Alloy

NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolyte attracts attention because of its stability in the air and water and its chemical stability with high-voltage cathode materials. However, LATP solid electrolyte has interfacial problems, such as limited contact area. Additionally, Li/LATP interface is deteriorated by structural collapse due to its reduction products. Herein, we modified the electrode interface using PEO based protecting layer (PL) and Li-In alloy anode. PEO based protecting layer (PL) was applied to suppress the Li/LATP interface side reactions and minimize the LiFePO4 (LFP) /LATP interfacial resistance. We applied two kinds of PLs, solid polymer electrolyte (SPE) and composite polymer electrolyte (CPE). A CPE was prepared using a ceramic filler of LLZTO in order to improve the ionic conductivity and long-term cycling stability of PL. As an anode material Li foil and In1.5Li foil were utilized. The symmetric and full cells were prepared with a PL coated on both sides of the electrolyte. The symmetric cell consisted of Li/PL/LATP/PL/Li and the full cell consisted of Li (or In1.5Li) /PL/LATP/PL/LFP. The symmetric cell and full cell with CPE exhibited stable cycling performance, compared to that with SPE. The symmetric cell utilizing In1.5Li foil showed higher overpotential during the initial cycles, but it showed improved cycling stability, compared to that with Li metal foil. XRD and TOF-SIMS results indicate that there were no structural and chemical changes in the LATP coated with PL. Therefore, the modification strategies of CPE protecting layer and Li-In alloy anode are effective for enhancing cycling performance in all-solid-state batteries.

(Invited) Electrolytes for Next-Generation Sodium Metal Batteries

Developing reliable and cost-effective electrical energy storage systems (EESs) for portable electronics, electric vehicles, and grid storage applications is vital. Na-ion batteries are the most promising alternative technology owing to their natural abundance and low sodium cost.[1] Solid-state batteries (SSBs) have garnered extensive attention for their ability to suppress the safety hazards of organic liquid electrolytes by replacing them with solid electrolytes.[2] Among the various solid electrolytes being explored, our group mainly focuses on NASICON (Sodium superionic conductor) type silicate and solid polymer electrolytes. Sodium silicates are a class of materials with composition, NaxMxSixOx (M = rare-earth metals, x = integer (1-10)).[3] They have the advantage of low sintering temperature (~1050 °C) and 3D framework structure containing MO6 octahedra and SiO4 tetrahedra providing facile ionic movement.[4] Solid polymer electrolytes (SPE) are known for their flexibility and electrode compatibility. Highly conductive, filler-free composite solid polymer electrolyte films were prepared using poly(vinylidene fluoride), poly(vinyl pyrrolidone) (PVP), and NaPF6.[5] PVP binder played an essential role in improving Na ion conductivity and excellent plating−stripping performance. This talk will present an overview of these solid electrolytes for next-generation sodium metal batteries.

Multifunctional single-ion conductor-integrated PEO-based solid polymer electrolytes endow highly stable and dendrite-free lithium metal batteries

Poly(ethylene oxide) (PEO) based solid polymer electrolytes (SPEs) hold great promise for circumventing the safety issues caused by liquid electrolytes, which are widely used as one of the leading technical strategies for constructing solid-state lithium metal batteries (LMBs). Unfortunately, developing PEO-based SPEs applicable to high-performance LMBs remains challenging due to the uncontrolled formation of lithium dendrites and sluggish ion migration. In this study, we present the fabrication of highly conductive and mechanically robust composite SPEs (CSPEs) for use in dendrite-proof LMBs by adding a new bis(sulphonyl)imide-based single-ion conductor (LiPEBI) as functional polymer fillers into PEO SPEs network. As expected, the as-prepared CSPEs can simultaneously achieve an excellent mechanical strength of 2.1 MPa, a considerable elongation at a break of 1491.0%, and an optimized degree of crystallization of 37.1%. In addition, introducing the LiPEBI additive promotes the homogeneous distribution of Li-ions and accelerates the ionic transport, resulting in an enhanced ionic conductivity of 4.17 × 10−4 S cm−1 and lithium ion transference number (tLi+) of 0.45 at 60 °C for CSPEs. Such comprehensive physical and electrochemical performances are favorable to suppressing lithium dendrite growth and prolonging the lifespan of LMBs. As a result, the Li||Li symmetrical cells assembled by the CSPEs display a remarkably stable cyclic performance with an extremely low voltage polarization of 60.3 mV over 500 h under 50 μA cm−2 at 60 °C. Also, the CSPEs-based Li||LiFePO4 batteries illustrate superior rate performance up to 1 C and deliver long-term cycling stability with a high discharge capacity of 128.8 mAh g−1 after 100 cycles under 0.4 C at 60 °C. We believe the novel CSPEs have great potential for actual application in the construction of high-safety and dendrite-free solid-state LMBs.

Anionic Anchoring Enhanced Quasi Solid Composite Polymer Electrolytes for High Performance Lithium Metal Battery.

Herein, ZIF-8 inorganic particles with different sized reinforced poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) solid composite polymer electrolytes (PVDF-HFP/10%ZIF-8) were prepared via a facile blade-coating approach, and free-standing quasi solid-state composite electrolytes (PVDF-HFP/10%ZIF-8(0.6)/Plasticizer, abbreviated as PH/10%ZIF-8(0.6)/P), were further obtained through the introduction of plasticizer. Optimized PH/10%ZIF-8(0.6)/P exhibited a high ionic conductivity of 2.8 × 10-4 S cm-1 at 30 °C, and superior Li+ transfer number of 0.89 with an ultrathin thickness (26 µm). Therefore, PH/10%ZIF-8(0.6)/P could effectively inhibit the growth of lithium dendrites, and the assembled Li/LiFePO4 cell delivered good cycling stability with a capacity retention rate of 89.1% after 100 cycles at 0.5 C.

Dual-layer composite solid polymer electrolytes with Janus properties for interface modification of solid state lithium metal batteries

Solid polymer electrolytes are widely applied in lithium metal batteries owing to good flexibility and machinability. However, monolayer polymer electrolyte are difficult to simultaneously satisfy the interfacial contact with the cathode and Li anode. Herein, the dual-layer composite solid polymer electrolyte with polypropylene film (CSPE@PP) are designed to promote the interfacial compatibility between the solid electrolytes and electrodes. The X-ray photoelectron spectroscopy (XPS) results confirm that poly (vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) can react with Li metal to form LiF layer, restraining the Li dendrite growth. Meanwhile, the polyacrylonitrile (PAN) antioxidant layer strengthens the contact stability between the electrolytes and the cathodes. Moreover, the PP film serves as the electrolyte's skeleton and connecting layer, enhancing the ion diffusion and mechanical strength of the solid electrolytes. As a result, the Li||CSPE@PP||Li cell is able to stably cycle over 400 h at 0.1 mA cm−2. The LFP||CSPE@PP||Li solid-state batteries deliver 141.98 mAh g−1 discharge capacity and high retention rate (91.1%) after 100 cycles at 0.1C. This work provides a viable strategy for expanding the application of composite solid polymer electrolyte (CSPE) in lithium metal batteries.

Fully Printed Electrolyte‐Gated Transistor Formed in a 3D Polymer Reservoir with Laser Printed Drain/Source Electrodes

AbstractIn solution processed electronic devices it is crucial that the deposited inks are properly aligned and that all post‐processing steps are compliant with each other. Moreover, shorter channel lengths are highly beneficial to increase the device performance. Herein, laser printing of metals and polymer reservoirs allows to print sub‐micrometer sized channel lengths while confining functional inks into these small gaps. Therefore, a manufacturing concept and optimized material stack, suitable for combined inkjet and laser printing are proposed. A nanoparticulate indium oxide (In2O3) semiconductor is inkjet printed into and constrained by a 3D laser written polymer (pentaerythritol triacrylate, PETA) reservoir. Inside the 3D printed polymer reservoir, platinum (Pt) electrodes, that are further routed over the reservoir walls, are laser printed by a metal reduction process. The transistor fabrication is completed by a second inkjet printed layer of composite solid polymer electrolyte and an organic top‐gate layer (PEDOT:PSS). This concept does not exceed annealing temperatures higher than 100 °C, and is compatible with a range of substrates. The characterized electrolyte‐gated field‐effect transistor show a reasonable on/off‐ratio in the range of 104 with negligible leakage currents. This materials and hybrid device manufacturing scheme has believed great potential for bioelectronics, lab‐on‐a‐chip applications and others.

Gelatin network reinforced poly (vinylene carbonate-acrylonitrile) based composite solid electrolyte for all-solid-state lithium metal batteries

Solid polymer electrolyte (SPE) has become one of the most promising candidate materials for building solid-state lithium batteries because of its excellent flexibility, expansibility and good interface compatibility with electrodes. However, SPE still has some problems such as low ionic conductivity at room temperature and narrow electrochemical window. Therefore, it is of great significance to develop polymer solid electrolyte with new structure to improve the comprehensive performance of the battery. In this work, Poly (vinylene carbonate-acrylonitrile) (PVN) was selected as the matrix of polymer electrolyte, and the network structure filled with biomass material gelatin was used as the skeleton. The composite solid polymer electrolyte (CSPE) composed of PVN, lithium bis (trifluoromethyl) sulfonimide (LiTFSI) and gelatin was prepared by simple solution casting method. The constructed PVN/LiTFSI/Gelatin (PLG) electrolyte has excellent ionic conductivity (3.47 × 10−4 S cm−1 at 60 °C) and wide electrochemical window (4.3 V). Li|10 %PLG CSPE|LiFePO4 battery has a capacity retention rate of 85 % after 1000 cycles of stable operation at 1C rate at 60 °C, and has excellent cycle performance and life. In addition, a low interface resistance enables highly reversible Li|Li symmetrical battery has a stably cycle of 1500 h at 0.1 mA cm−2 and has good interface compatibility. Therefore, PLG CSPE composite is a simple and effective strategy to obtain high-performance lithium batteries, which can realize the ultra-stable operation of solid lithium metal batteries.

Dual-type gel polymer electrolyte for high-voltage lithium metal batteries with excellent cycle life

The most attractive approach for maximizing the energy density of rechargeable lithium batteries is to combine a lithium metal anode with a high-voltage cathode. However, the dendritic formation of lithium at the anode and the highly oxidizing conditions that cause electrolyte decomposition at the cathode have hindered the practical development of lithium metal batteries (LMBs). In this study, we report a dual-type gel polymer electrolyte (GPE) composed of an anolyte and a catholyte that can address the drawbacks of both the anode and cathode sides. The anolyte is a poly(ethylene oxide)-based composite solid polymer electrolyte that is chemically stable with lithium metal and has a high mechanical strength for suppressing lithium dendrite growth. A cross-linked gel polymer electrolyte with high lithium-ion conductivity and oxidative stability was used as the catholyte. The Li/LiCoO2 cell assembled with a dual-type GPE exhibited a high discharge capacity of 181.1 mAh g−1 (areal capacity: 3.15 mAh cm−2) in the voltage range of 3.0–4.5 V and excellent cycle life, with a capacity retention of 74 % after 700 cycles at 25 °C and 0.5 C rate. Our study proposes a promising electrolyte system for LMBs with high energy density and good cycle life.

PEO-Based Solid Composite Polymer Electrolyte for High Capacity Retention All-Solid-State Lithium Metal Battery.

The limited ionic conductivity at room temperature and the constrained electrochemical window of poly(ethylene oxide) (PEO) pose significant obstacles that hinder its broader utilization in high-energy-density lithium metal batteries. The garnet-type material Li6.4 La3 Zr1.4 Ta0.6 O12 (LLZTO) is recognized as a highly promising active filler for enhancing the performance of PEO-based solid polymer electrolytes (SPEs). However, its performance is still limited by its high interfacial resistance. In this study, a novel hybrid filler-designed SPE is employed to achieve excellent electrochemical performance for both the lithium metal anode and the LiFePO4 cathode. The solid composite membrane containing hybrid fillers achieves a maximum ionic conductivity of 1.9 × 10-4 S cm-1 and a Li+ transference number of 0.67 at 40°C, respectively. Additionally, the Li/Li symmetric cells demonstrate a smooth and stable process for 2000 h at a current density of 0.1mA cm-2 . Furthermore, the LiFePO4 /Li battery delivers a high-rate capacity of 159.2 mAh g-1 at 1 C, along with a capacity retention of 95.2% after 400 cycles. These results validate that employing a composite of both active and inactive fillers is an effective strategy for achieving superior performance in all-solid-state lithium metal batteries (ASSLMBs).

AlTiMgLiO medium entropy oxide additive for PEO-based solid polymer electrolytes in lithium ion batteries

Solid polymer electrolytes (SPE) have attracted considerable attention as electrolytes for solid-state batteries due to their toughness, high safety, and ionic conductivities that can be comparable with liquid electrolytes, especially at higher temperatures. However, polymers have low elastic moduli, which decrease at higher temperatures, limiting their ability to reduce dendrite formation. Mechanical blocking is one method of improving the interfacial layer and reducing dendritic growth but requires the elastic modulus of the polymer to be high enough to suppress lithium dendrites growth. Previous studies have focused on using unary metal oxides, which are limited by the percent of additives that can be included in the polymer before causing negative effects on electrochemical properties. In this study, we demonstrate a new strategy for improving the performance of polymers by synthesizing a multielement oxide (MEO) filler, AlTiMgLiO, to create a composite SPE with enhanced electrochemical performance. The synthesized AlTiMgLiO-containing SPE resulted in a voltage window of 0–6.18 V and a lithium transference number of 0.42. The overpotential voltage during galvanostatic cycling was reduced due to the improvements made to the morphology. The improvement of the interfacial layer reduced Li dendritic growth, resulting in a capacity of 99.68 mAh g−1 after 500 cycles, and a capacity retention of 78.69 %. The possible reasons for the improvement are discussed, providing a direction for future studies on the use of multielement materials as fillers in solid polymers electrolytes.